The overall objective of this competing R01 renewal is the continued development of the Elastin Fusion Protein technology as a genetically encodable, bioinspired analog of "smart" -stimulus responsive- protein-polymer conjugates. In this renewal application, we seek to greatly expand upon our ability to modulate the solution behavior of ELP fusion proteins by introducing a greater level of sophistication beyond simple physical triggers of the ELP phase transition and uncontrolled aggregation as the final state, by developing new strategies for the: (1) stimulus responsive self-assembly of ELP fusion proteins into micelles or other self-assembled nano-mesoscale structures;and (2) coupling molecular recognition to the phase transition of ELPs, so that ELP fusion proteins can be programmed to exhibit an isothermal phase transition in response to ligand-binding. These "second-generation" ELP fusion proteins will, we believe, provide a new set of applications in Biotechnology and Medicine by virtue of the increased sophistication of the functionality embedded in these ELPs. For example, the ability to trigger an LCST transition by biochemical ligand-binding to an ELP fusion protein will provide a simple, convenient and modular approach to design biopolymer actuators that exhibit ligand-binding triggered phase transition behavior by splicing together ligand binding domains with ELPs. Similarly, developing a generic methodology to convert a peptide or protein into a nanoscale construct such as a spherical micelle has implications for the delivery of protein therapeutics because: (1) it will increase the apparent size of the biomolecule and will thereby increase its in vivo half-life;and (2) will provide a rational strategy to enhance the affinity and specificity of a protein or peptide drug for its target receptor via multivalency. PUBLIC HEALTH RELEVANCE: This project will develop bioinspired "smart" -stimulus responsive- Elastin fusion proteins. In this renewal application, we seek to greatly expand upon our ability to modulate the solution behavior of ELP fusion proteins by developing a new generation of ELP fusion proteins that will self-assemble into nanoparticles of defined size and shape or that will exhibit soluble-insoluble phase transition behavior upon binding to another molecule. These ELP fusion proteins will provide new molecular building blocks that will enable new approaches for targeted drug delivery, regenerative medicine and bioanalytical assays.